1. Field of the Invention
This invention relates to an air conditioner for an automobile. More particularly, the invention relates to an improvement in an instantaneous cooling or warming performance.
2. Description of the Related Art
The temperature inside a passenger compartment of an automobile rises while the car is parked, in summer, due to solar radiation. The need for instantaneous cooling inside the passenger compartment is high under such a condition. In existing automobile air conditioners, airflow ducts for distributing air-conditioning air are fitted to an interior air conditioner unit and cooling air is sent to each blow-out port, inside the passenger compartment, such as a defroster blow-out port, a face blow-out port, a foot blow-out port, and so forth, and the temperature of each airflow duct rises during parking in summer. Therefore, the cooling air receives heat, for the airflow ducts that are heated, and is heated even when instantaneous cooling is desired. The instantaneous cooling performance is thus deteriorated.
The temperature inside the passenger compartment drops due to the cold external air, while the car is parked, in winter. Under such conditions, the cooling water of an automobile engine is not sufficiently heated for several minutes at the starting of the automobile and a hot water system heater using this cooling water as a heat source fails to provide a feeling of warmth. Another problem is that demisting and defrosting of a front windshield and side window glass cannot be done because hot air is not blown out. Furthermore, it has become more difficult to secure sufficient warming calorific power, from engine cooling water alone, as the efficiency of the automobile engines has become higher in recent years.
Under the circumstances described above, the need for instantaneous warming inside the passenger compartment is high. In existing automobile air conditioners, airflow ducts for distributing air-conditioning air are fitted to the interior air conditioner unit and cooling air is sent to each blow-out port, inside the passenger compartment, such as the defroster blow-out port, the face blow-out port, the foot blow-out port, and so forth. Japanese Unexamined Patent Publications No. 60-8110 and No. 6-8015 can be cited as prior art references relating to instantaneous warming. The former disposes an electric heater inside the blow-out port arranged in an automobile door and the latter disposes an electric heater inside a branch duct branching from a main duct.
The temperature of the airflow duct greatly drops due to an external air temperature during parking in winter. Therefore, according to the prior art technologies described above, the hot air loses heat to the cold airflow ducts and is cooled even when instantaneous warming is desired, with the result being a deterioration in the instantaneous warming performance. Because the electric heater must be arranged in these technologies, the problems of space, an increase of the production cost and an increase in the weight, occur. In addition, the electric heater is operated only for instantaneous warming, and the airflow resistance inside the airflow duct increases at other times.